cc: Fork OverlayCandidate to CALayerOverlay

cc/output/direct_renderer.cc

Index: cc/output/direct_renderer.cc
diff --git a/cc/output/direct_renderer.cc b/cc/output/direct_renderer.cc
index 0a66eea2ae10bab6c2007d7e50fe60ea2c94d924..1b959cae13cf4b453d64053e19fbd7aef99f9d57 100644
--- a/cc/output/direct_renderer.cc
+++ b/cc/output/direct_renderer.cc
@@ -198,7 +198,7 @@ void DirectRenderer::DrawFrame(RenderPassList* render_passes_in_draw_order,
       "Renderer4.renderPassCount",
       base::saturated_cast<int>(render_passes_in_draw_order->size()));
 
-  const RenderPass* root_render_pass = render_passes_in_draw_order->back();
+  RenderPass* root_render_pass = render_passes_in_draw_order->back();
   DCHECK(root_render_pass);
 
   DrawingFrame frame;
@@ -207,6 +207,8 @@ void DirectRenderer::DrawFrame(RenderPassList* render_passes_in_draw_order,
   frame.root_damage_rect = Capabilities().using_partial_swap
                                ? root_render_pass->damage_rect
                                : root_render_pass->output_rect;
+  frame.root_damage_rect.Union(next_root_damage_rect_);
+  next_root_damage_rect_ = gfx::Rect();
   frame.root_damage_rect.Intersect(gfx::Rect(device_viewport_rect.size()));
   frame.device_viewport_rect = device_viewport_rect;
   frame.device_clip_rect = device_clip_rect;
@@ -239,9 +241,16 @@ void DirectRenderer::DrawFrame(RenderPassList* render_passes_in_draw_order,
   // If we have any copy requests, we can't remove any quads for overlays,
   // otherwise the framebuffer will be missing the overlay contents.
   if (root_render_pass->copy_requests.empty()) {
-    overlay_processor_->ProcessForOverlays(
-        resource_provider_, render_passes_in_draw_order, &frame.overlay_list,
-        &frame.root_damage_rect);
+    if (overlay_processor_->ProcessForCALayers(
+            resource_provider_, render_passes_in_draw_order,
+            &frame.ca_layer_overlay_list, &frame.overlay_list)) {
+      // Ensure that the next frame to use the backbuffer will do a full redraw.
+      next_root_damage_rect_.Union(root_render_pass->output_rect);
+    } else {
+      overlay_processor_->ProcessForOverlays(
+          resource_provider_, render_passes_in_draw_order, &frame.overlay_list,
+          &frame.root_damage_rect);
+    }
   }
 
   for (size_t i = 0; i < render_passes_in_draw_order->size(); ++i) {